Implantable cardiac defibrillator (ICD) systems are used to deliver high energy electrical pulses or shocks to a patient's heart to terminate life threatening arrhythmias, such as ventricular fibrillation. Traditional ICD systems include a housing that encloses a pulse generator and other electronics of the ICD and is implanted subcutaneously in the chest of the patient. The ICD is connected to one or more implantable medical electrical leads that are implanted within the heart, referred to herein as transvenous leads.
Traditional ICD systems that utilize transvenous leads may not be the preferable ICD system for all patients. For example, some patients with difficult vascular access precludes placement of transvenous leads. As another example, children and other younger patients may also be candidates for non-transvenous ICD systems. Moreover, transvenous leads may become fibrosed in the heart over time, making lead revision and extraction procedures challenging.
An extravascular ICD system may be preferred for these patients. An extravascular ICD system includes a lead (or leads) that are implanted extravascularly in the patient, e.g., outside and/or exclusive of the heart. As such, the extravascular ICD may eliminate the need to implant transvenous leads within the heart. Instead, the lead(s) may be implanted subcutaneously, substernally, or in other extravascular locations.